This invention generally relates to dilatation catheters for use in percutaneous transluminal coronary angioplasty (PTCA) procedures and particularly to over-the-wire dilatation catheters for such use.
In classic PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient and advanced therein until the preshaped distal tip thereof is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from its proximal end, which extends outside of the patient, to turn the distal tip of the guiding catheter so that it can be guided into the coronary ostium and seated therein. In an over-the-wire dilatation catheter system, a guidewire is slidably disposed within an inner lumen of the dilatation catheter and the assembled catheter and guidewire are introduced into and advanced through the proximal end of the guiding catheter to the distal tip of the guiding catheter seated within the coronary ostium. The distal tip of the guidewire is usually manually shaped (curved) by the physician or one of the attendants before it is introduced into the guiding catheter along with the dilatation catheter.
The shaped distal tip of the guidewire is first advanced out the distal tip of the guiding catheter into the patient's coronary artery. To guide the curved or otherwise shaped distal end of the guidewire into a targeted branch artery having a stenosis which to be dilated, a torque is applied to the proximal end of the guidewire, which extends out of the proximal end of the guiding catheter, as it is advanced within the coronary anatomy. The advancement of the guidewire within the target artery continues until the distal end of the guidewire crosses the lesion to be dilated.
The dilatation catheter is then advanced out of the distal tip of the guiding catheter into the patient's coronary anatomy, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the stenosis to be dilated. Once properly positioned across the stenosis, the flexible, relatively inelastic dilatation balloon on the dilatation catheter is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations of the balloon may be required to complete the dilation. After the last dilation, the balloon is deflated so that the dilatation catheter can be removed from the dilated stenosis and blood flow can resume through the dilated artery.
Further details of guiding catheters, dilatation catheters, guidewires, and other devices for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,438,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); U.S. Pat. No. 4,582,185 (Samson); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,898,577 (Badger et al.); U.S. Pat. No. 4,748,982 (Horzewski et al.) and U.S. Pat. No. 4,821,722 (Miller et al.) which are hereby incorporated herein in their entirety by reference thereto.
On going development work has reduced the transverse dimensions of dilatation catheters for angioplasty procedures both as to their outer diameters as well as the wall thicknesses of the tubular components. This has led to difficulties in designing dilatation catheters having small transverse dimensions with adequate pushability for advancement through guiding catheters, deep into the patient's coronary artery and across tight stenoses. The marginal or inadequate pushability has been particularly noticeable with over-the-wire catheters adapted for use with guidewires having diameters not more than about 0.014 inch (0.356 mm), particularly not more than about 0.012 inch (0.305 mm). What has been needed and heretofore unavailable is a small diameter, thin-walled over-the-wire dilatation catheter which can be pushed through guiding catheters of various distal shapes and deep within a patient's coronary artery over small diameter guidewires with good tracking and distal flexibility. The present invention satisfies this and other needs.